Method of manufacturing a beam

ABSTRACT

A method of manufacturing a beam comprises rolling, in a longitudinally profiled rolling process, two flange pieces ( 6,7 ), such that one surface ( 8 ) of each rolled flange piece is profiled according to a predetermined thickness profile; and joining ( 12,13 ) the rolled flange pieces together via a web of the beam or by profiled surfaces of the flanges.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§371 national phase conversionof PCT/EP2014/050365, filed Jan. 10, 2014, which claims priority ofGreat Britain Patent Application No. 1302281.9, filed Feb. 8, 2013, thecontents of which are incorporated by reference herein. The PCTInternational Application was published in the English language.

TECHNICAL FIELD

This invention relates to a method of manufacturing a beam, inparticular for structural metal beams.

TECHNICAL BACKGROUND

Universal beams also known as I-beams or H-beams are regularly used inbuilding structures. However, the type of beam that is commonly used isnot as efficient or optimised as it could be. Typically, the beams areof constant cross section along their length. The size of cross sectionis selected from a list of catalogue sizes and chosen based on themaximum bending moments and shear forces expected in use. There may beadditional criteria such as buckling limits and allowances for holes.The size of the cross section is therefore based on the worst casecondition along the length of the beam. However, in practice thesesizing criteria do not apply to all points along the length of the beam,so at points along the beam the beam is over specified; it has excessmaterial and excess weight that is not required.

One reason why the majority of universal beams have a constant crosssection along their length is that most of these beams are rolled inuniversal beam rolling mills and the standard technology in this type ofmill does not allow the beam cross section to be varied along the lengthof the beam.

Recently there have been various attempts to overcome this restriction.WO2012032301 describes apparatus and methods for rolling beams withvariable depth, variable flange thickness, variable flange width etc.EP0756905 describes a related technology whose main purpose is toachieve consistent overall beam depth for different flange thicknesses.JP2000343102 describes another method of producing beams with variableweb depth and flange thickness. These methods have several significantdisadvantages. The main problem is that the material flow patternsinvolved in rolling a one piece beam with variable cross section alongits length are very complex and it is difficult to achieve the correctmaterial properties and to avoid undesirable curvature of the beam.Another issue is that new equipment is required.

To avoid the difficulties involved in rolling a beam with varying crosssection along its length an alternative manufacturing method is tofabricate the beam, that is to construct the beam by welding or joiningplates or sections together. The construction of fabricated beams iswell known, for example as described in U.S. Pat. No. 1,843,318, wherearched beams are provided, or truss beams as illustrated in U.S. Pat.No. 620,561 where the depth is modified by cutting material from the weband then joining the cut edges together. A characteristic of these beamsis that the thickness of the material in the web and the flange isconstant along the length of the beam. The only thing which changesalong the length of the beam is its depth. Another well known type offabricated beam is the castellated or cellular beam although in generalthis construction is used to increase the beam depth relative to itsparent section along the full length of the beam and not specifically tovary the section along the length of the beam. A significantdisadvantage of these prior art fabricated beam designs is that becausethe web thickness and flange thickness are constant along the length ofthe beam the change in section can only be achieved by modifying the webdepth or the flange width. Whilst changing the web depth or flange widthis acceptable for some applications, in building applications it ispreferable to have beams of constant depth and constant flange width tomake the fitting of floor slabs, ceiling parts and walls simple.

In FIG. 5 of JP2000343102 a beam which changes section part of the wayalong its length is illustrated. This beam consists of two separateI-beams with different flange thicknesses, but with the same web depthwelded together. It is clear that by welding several different I-beamsections together it would be possible to produce beams in which thecross section varies along the length, but this has severaldisadvantages. Firstly in order to approximate the varying loadrequirements along the length of the beam reasonably accurately a largenumber of different sections would be required and welding all of thesesections together whilst maintaining the straightness of the beam wouldbe difficult. Secondly the welds in the flanges of the beam wouldpotentially weaken the beam.

Another method of producing a beam with the ideal variation in crosssection along its length is to machine the beam out of either a solidbar or out of a beam which starts with a constant cross section alongits length, equal to, or greater than the maximum cross sectionrequired. A related method is to fabricate the beam from plates orsections which have been machined to give variations in thickness alongtheir length. However, these methods of manufacture are extremelywasteful of material and expensive and are typically only used for beamsin things like aircraft. They are not practical or cost effectivesolutions for beams in building construction.

Another method of producing a beam with a variation in cross sectionalong its length is to fabricate the beam using longitudinally profiled(LP) plates. The rolling of LP plates in which the thickness of theplate varies along the length of the plate is well known and such platesare commonly used in shipbuilding and bridge building. Large I-beamshave been fabricated using longitudinally profiled plates as describedby Schroter in “Heavy steel plates for efficient constructionalsteelwork” and Richter and Schmackpfeffer in “Longitudinally profiledplates cut costs”. However, the application of LP plates in thefabrication of I-beams has so far been limited to very large structuressuch as bridges, power stations and very tall buildings. I-beams forgeneral constructional use in buildings still mostly use constantcross-sections. One of the reasons for this is that the production of LPplates in which the thickness varies smoothly over the relatively shortlength of a standard building I-beam has not been practical.

U.S. Pat. No. 3,335,596 describes manufacturing an H section beam, thenapplying projections to the surface of its flanges by a rolling pass ina finishing mill using rollers having grooves or notches.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention a method ofmanufacturing a beam comprises rolling, in a longitudinally profiledrolling process, two flange pieces, such that one surface of each rolledflange piece is profiled according to a predetermined thickness profile;and joining the rolled flange pieces together via the profiled surfaces.

Preferably, the method further comprises rolling the flange pieces suchthat another surface of each rolled flange piece is substantially flat.

The rolling process imparts a profile to one face of the flange piece,whilst keeping the opposite surface flat, so that the beam has therequired strength at various points along its length without extramaterial and weight being used unnecessarily, as well as having theconvenience for the end user of a flat surface.

Preferably, the method further comprises rolling the two flange piecestogether and back to back.

Preferably, the rolled flange pieces comprise T shaped flange pieces.

Preferably, the flange surfaces of the manufactured beam remote from theweb are substantially flat and parallel.

In accordance with a second aspect of the present invention, a method ofmanufacturing a beam comprises rolling, in a longitudinally profiledrolling process, a flange piece, such that a plurality of surfaces ofthe rolled flange piece are profiled according to a predeterminedthickness profile; wherein the longitudinally profiled rolling processcomprises rolling Y-shaped sections; and finishing the Y-shaped sectionsto form T-shaped sections; and wherein the method further comprisesjoining two of the rolled flange pieces together via a profiled surfaceof each flange piece.

Preferably, the method further comprises providing a correspondingrolled web piece and joining the rolled flange pieces via the rolled webpiece.

A profiled surface of each flange piece is joined to a correspondinglyprofiled surface of the web piece to join the two flange piecestogether.

Preferably, the method further comprises manipulating one or more rollsduring the rolling operation in order to vary individual beam dimensionsalong the beam length.

Preferably, the method further comprises casting raw material with atleast part of the required thickness variation already present in thecast material and rolling the cast material.

The present invention provides a fabricated beam which is constructedfrom one or more LP plates with one flat side and one profiled side orfrom one or more T-sections in which the thickness of the flange partvaries along the length of the beam, so that those parts at which higherforces are applied have additional material for strength and areas ofrelatively low loading have a reduced cross sectional area. It alsoprovides for an apparatus to produce T-sections with varying thicknessalong their length. The invention is able to produce a beam withconstant or almost constant depth and flange width, but with varyingflange and web thickness along its length to satisfy the requirement ofthe building industry for beams of constant depth and constant flangewidth to make the fitting of floor slabs, ceiling parts and wallssimple.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of a beam and a method of manufacturing a beam according tothe present invention will now be described with reference to theaccompanying drawings in which:

FIGS. 1 a and 1 b respectively illustrate a side view (1 a) and a crosssection (1 b) of a typical rolled universal beam;

FIG. 2 schematically illustrates a roll gap view of a conventionaluniversal beam mill;

FIGS. 3 a to 3 c respectively illustrate an exploded side view of a beam(3 a), a cross-section of an assembled beam (3 b) and a side view of theassembled beam (3 c) of a first example of a fabricated beam using LPprofiled plate for the flanges;

FIGS. 4 a to 4 e respectively illustrate prior art of a top view of aweb of varying thickness for a beam (4 a), a side view of the web (4 b),an end view of the web (4 c), an end view of a beam comprised of a webwith flanges (4 d) and a side view of the beam comprised of a web andflanges (4 e) of a second example of a fabricated beam using an LPprofiled plate for the web;

FIGS. 5 a to 5 g respectively illustrate a top view of a web (5 a), anend view of the web (5 b) and a side view of the web and of one flange(5 c) and an end view thereof (5 d), a cross sectional view (5 e), and aside view (5 f) of a web and two flanges assembled into a fabricatedbeam and a method of rolling the flanges of the beam using LP profiledplate with one flat side according to the present invention (5 g);

FIGS. 6 a to 6 d respectively illustrate the rolling of a T-section partwith a variable flange thickness (6 a), side view of the T-section part(6 b) and side views (6 c) and (6 d) of two variations of a beamassembled, and construction of a fabricated beam according to thepresent invention;

FIG. 7 schematically illustrates an alternative method of rolling theT-section parts according to the present invention;

FIG. 8 a illustrates a roll gap view of an alternative millconfiguration for rolling T-section parts according to the presentinvention and FIGS. 8 b and 8 c illustrate a side and a top view of anassembled T-shaped part formed from a Y-shaped part initially formed asin FIG. 8 a.

DESCRIPTION OF EMBODIMENTS

In a conventional universal beam as illustrated in FIGS. 1 a and 1 b,the beam 1 has an elongate web 2 and transverse flanges 3 at eachelongate edge at the top and bottom of the web. As can be seen from FIG.1 b, the thickness 4 of the flanges along their entire lengths, thedepth 5 b of the web 2, i.e. its height between its flanges 3 in FIGS. 1a and 1 b and the depth 5 of the beam, i.e. the height of the beamincluding its thickness of its flanges 3 is constant along the length ofthe beam. Since the cross section is constant and must meet the maximumload requirements along the length of the beam, then at those pointsalong the length at which the maximum loading is not experienced thereis more material than is actually required.

FIG. 2 illustrates the final rolling step in a conventional universalbeam mill in which rolls 101, 103 roll the flanges by exerting a rollforce 105, 106, whilst rolls 102, 104 roll the web by exerting a rollforce 107, 108. In practice, universal beam mills usually roll theI-beam on its side, as an H-beam, but the principle is the same as thatillustrated in FIG. 2.

The present invention provides a beam and methods of manufacturing abeam which enable the profile to be tailored to the loading requirementsat each point along the beam, rather than using the maximum loadrequirement throughout. By continuously matching the section propertiesto the stress of the beam along its length, a mass reduction of the beamis possible. This is achieved by continuously determining the mostefficient cross section possible whilst satisfying all standards, codesand regulations throughout the length of the beam.

Recent developments such as those described in GB1213011.8 make itpossible to produce plates with multiple changes in thickness in theshort length of a standard building I-beam and to efficiently producethese LP plates by shearing the as-rolled length into several shorterlengths each with a longitudinal profile. This makes it possible toconstruct fabricated beams for general building use in which the flangethickness or the web thickness or both vary along the length of thebeam. However beams for general constructional use in buildingsfabricated from LP plates still suffer from certain problems. Oneproblem is that it is difficult to achieve a flat top and bottom faceand constant beam depth with conventional LP plates. Another problemwith fabricated beams constructed from LP plates is that the welds aresituated at the interface or corner between the flanges and the web inareas of high stress and thus they potentially weaken the beam.

FIGS. 3 a, 3 b and 3 c illustrates a fabricated beam constructed from LP(longitudinally profiled) plates for the flanges. The thicknessvariation along the length of the plates of the flanges and of the webincludes multiple points of inflection as described in GB 1213011.8. Intypical applications, the maximum loads in the beam are not at the endsof the beam, but in the center and the minimum loads are not at theends, but part way along the beam. Profiles such as those illustrated inFIGS. 3 a to 3 coptimizes optimize the beam cross section for thisvariation in the loads along the length. FIG. 3 a shows a side view oftwo LP plates for flanges 31, 32 and a plate for the web 33. In thisexample, the web is constant thickness, but it could also bemanufactured from LP plate as well. In this example, the web of the beamhas been cut into a shape 36 having a depth to match the heights in FIG.3 a of the thickness profiles of the flanges, although if the variationin flange thickness is not very large, then this may not be necessaryand a web piece with straight edges may be welded directly to the LPprofiled flanges 31, 32. Welds 34, 35 in FIG. 3 c which join the flanges31, 32 and the web together are situated directly at the interfaces orcorners between the web 33 and each flange 31, 32 and are thus in ahighly stressed area of the beam. Top and bottom faces of the beam 37,38 are not completely flat because LP rolled plates vary in thicknessrelative to their centreline. With LP plates which are rolled as simpletapers as illustrated in Schroter and in Richter and Schmackpfeffer itis possible to achieve flat top and bottom faces, but with more complexcurved profiles it is not possible to get flat top and bottom facesunless the LP plates are specially straightened after rollingspecifically to achieve one flat side. In practice some variation in theoverall depth (heights in FIG. 3 c) of the beam can be tolerated inbuilding construction and so the LP plates would not always need to bestraightened. However, beams with large variations in flange thicknessalong their length would need to be straightened in order to remain withthe required tolerances for the overall beam depth.

FIGS. 4 a to 4 e illustrate views of components of and an assembledalternative fabricated beam construction according to the known priorart. In FIG. 4 d, the beam is constructed from two constant thicknessflanges 18, 19 which are welded to a variable thickness LP rolled web23. The web 23 varies in thickness between its thinnest part 22 andthickest part 21. In FIG. 4 e, welds 12, 13 join the web 23 to theflanges 18 and 19, respectively. This construction has the advantageover the construction in FIG. 3 that the beam has constant overall depth(height in FIG. 4) without any straightening of the LP rolled plate.However this type of construction in which it is only the web thicknesswhich changes along the length of the beam is not as efficient atminimising the weight of the beam as the type with variable flangethickness. Also this beam construction still suffers from the fact thatthe welds are in the corner between the web and the flange in a highlystressed area.

Combining the LP flanges illustrated in the embodiment in FIG. 3 hereofwith the LP web illustrated in prior art FIG. 4 would still suffer fromthe same problems as the beam illustrated in FIG. 3 in that the overalldepth would vary along the length and the welds are in a highly stressedarea.

FIGS. 5 a to 5 g illustrate a beam and a method of rolling the flangesof a beam according to one aspect of the present invention. In order toproduce a beam with constant overall depth along its length, each flange6, 7 is produced with one flat surface 10 as in FIG. 5 f and oneprofiled surface 8, 11 as in FIGS. 5 a and 5 c. Use of a longitudinallyprofiled rolling process results in the thickness of a plate beingrolled varying along the length of the plate, wherein the plate beingrolled forms the two flanges of the beam. One profiled surface of eachflange has a profile which varies in thickness along its length.According to one aspect of the present invention, this is achieved byrolling using rolls 201, 202, to profile the two flanges 6, 7 as in FIG.5 a back to back as a pack with a separator layer or compound 51 betweenthem as illustrated in FIG. 5 a and FIG. 5 b. The use of separatorcompounds is well known in clad plate rolling for example. Referring toFIG. 5 g, after their rolling, the two flanges 6, 7 are separated fromeach other. The flanges required for beams are usually much narrowerthan the width which a plate mill can roll. Therefore, for the mostefficient production the rolled pack has a width which is a multiple ofthe required flange width. After their rolling, the plates 6, 7 are cutto required flange widths as illustrated by the dashed lines 52. Theflanges produced in this way have one side 8, which is profiled and oneside 10 which is substantially flat. When these flanges 6, 7 arefabricated into a beam as illustrated as in FIGS. 5 c, 5 e and 5 f bywelding along the weld lines 12, 13 (FIGS. 5 c and 5 f) to acorrespondingly profiled web 9 of length 16 which has its deepest point14 where the flange is thinnest, the overall beam depth is substantiallyconstant along the length of the beam, whilst the flange thickness 15varies along the length. This is an improvement over the example of FIG.3, although it still suffers from having the welds 12, 13 in a highlystressed location.

FIGS. 6 a to 6 d illustrate the final stage of rolling of a T-shaped(T-section) part 61 according to a second embodiment of the presentinvention. The upper roll 60 has a groove 54 which accommodates the stem62 of the T. The lower roll 52 does not have a groove. By moving rolls60, 52 closer to each other, or further apart from each other, thethickness of the flange part 63 of the T section may be varied along thelength of the T section as illustrated in FIG. 6 b. Due to therestraining effect of the stem 62, careful guiding of the T-section 61is required during rolling in order to keep it straight. When thethickness of the flange part is changed, this naturally tends to modifythe height of the stem of the T as well. One option for the manufactureof the beam is to cut the web part to fit the variation in the height ofthe stem of the T. But, a simpler option is to cut the stem 62 of the Tat a constant height as illustrated by the dashed line 53 in FIG. 6 b.This means that the web part 57 in FIG. 6 c can have a constant depthand it makes construction of the beam simpler. The beam constructed fromtwo T-section parts 55, 56 with varying flange thicknesses and a webpart 57 has two welds 58, 59. These welds are located away from thecorner between the flange and the web and are thus less highly stressedthan the welds in the beams in the examples of FIGS. 3 and 4.

An even simpler construction may be achieved if the T-sections arerolled with sufficiently long stems that the required beam depth isachieved by simply welding the two stems 55, 56 together with a singleweld 501 as illustrated in FIG. 6 d. This has the additional advantagethat the weld is now in the ideal place which is on the neutral axis ofthe beam. However rolling T-sections with varying flange thickness withlong stems is more difficult than rolling them with short stems becauseof the restraining effect of the stem.

FIG. 7 illustrates an alternative method of rolling the T-section partsin which both upper roller 61 and lower roller 62 have grooves and twoT-sections 67, 68 are rolled back to back with a separator compound orlayer 66 between them. The use of separator compounds is well known inclad plate rolling for example. This method has the advantage that it iseasier to achieve straight T-sections because the top and bottom bendingforces during rolling balance each other out.

FIGS. 8 a to 8 c illustrate an alternative method of rolling theT-section parts for a beam according to the invention. The mill hasthree rolls 71, 72, 73 which can be moved closer to each other orfurther away from each other in order to vary the thickness of both theflange and the stem parts of the T-section. By analogy with theconventional beam rolling process, the step which is illustrated in FIG.8 a is the intermediate rolling stage in which a Y-shape 79 is rolled.In the final rolling stage the Y-shape is passed through a finishingstand similar to that in FIG. 6 a in order to convert the Y-shape into aT-shape (T-section). The advantage of carrying out the intermediaterolling in a Y-shape is that it is easier to achieve large thicknesschanges in the flange whilst keeping the material straight. In general,it is easier to achieve large thickness changes in the flange whilstkeeping the material straight if the same ratio of thickness change isapplied to the stem part. This is simple to achieve by adjusting thethree rolls together. Consequently the mill illustrated in FIG. 8 a iscapable of producing a Y-section which can be converted into a T-sectionwhich has both a long stem part and large thickness changes. Afabricated beam such as that illustrated in FIG. 8 b can then be made bywelding 77 the two T-sections 75, 76 together. If the ratio of thicknesschange in the web part is made comparable to that in the flange part,then the web of the beam also has thickness variations along its lengthas illustrated in FIG. 8 c. If a separate web component is required inorder to achieve the required overall beam depth as illustrated in FIG.6 c, then the web part can either be rolled with matching thicknessvariations or it can have constant thickness. FIG. 8 c shows FIG. 8 bviewed from above and illustrates how the web thickness 78 and flangethickness both vary.

The sectional properties of a beam may be influenced by varying a numberof geometrical parameters. The parameters addressed according to thepresent invention are the flange thickness and the web thickness. Thisavoids complication of the design and construction process bymaintaining the outer envelope dimensions of the beam, so that it canfit into any construction where a universal beam would have been usedpreviously. The T-sections with varying flange thickness may also beused to fabricate beams with variations in beam depth along theirlength.

All aforementioned embodiments of the invention can be produced usingstandard raw material geometry i.e. billets and plates as the feedstock.The stages required and forces required by the invention can be reducedif variable cast materials are used at the start of the process. Forexample a T-section which has large variations in thickness along itslength could be rolled from a cast product which already has somethickness variation along its length.

The examples of the present invention described above allow forimplementation of a set of beam profiles tailored to particularapplications, such as a specific office grid structure, which can bedesigned according to standard building codes and loading conditions.This means a final product can be manufactured as specified by thedesigner, rather than having to use standard products. For example, thebeams can be tailored to a specific structure, or a specific positionwithin that structure and a product specification for the beams canspecify the working limits of the mill or workshop allowing moreflexibility for the designer.

The invention has the benefit of maintaining parallel or almost parallelflange outer surfaces which are convenient for construction purposes, aswell as reducing the total amount of metal used in the construction. Inthe case of the beams constructed from T-sections the invention has theadditional benefit of moving the welds between the components away fromthe highly stressed areas of the beam. In each example, use of alongitudinally profiled rolling process results in a web or flangehaving a profile which varies in thickness along its length.

1. A method of manufacturing a beam, the method comprising: rolling, ina longitudinally profiled rolling process, two separate flange pieces,such that at least one surface of each rolled flange piece is profiledaccording to a predetermined thickness profile of the flange; orientingthe rolled flange pieces to have their respective at least one profiledsurface of each flange facing toward the other flange; and joining therolled flange pieces together by providing a web and between the facingsurfaces of the separate flange pieces.
 2. A method according to claim1, further comprising rolling the flange pieces and orienting the rolledflange pieces such that another of the surfaces of each rolled flangepiece that faces outwardly and away from the other flange piece issubstantially flat.
 3. A method according to claim 1, further comprisingthe rolling of the two flange pieces is performed on the flange pieceswhich are then together and back to back.
 4. A method according to claim1, wherein the rolled flange pieces comprise T shaped flange pieces. 5.A method according to claim 2, wherein the flange surfaces of themanufactured beam that face away from the other flange are substantiallyflat and parallel.
 6. A method of manufacturing a beam, the methodcomprising: rolling, in a longitudinally profiled rolling process, aflange piece having a plurality of surfaces; during the rolling process,providing the plurality of surfaces of the rolled flange piece with aprofile according to a predetermined thickness profile; thelongitudinally profiled rolling process comprises rolling at least oneY-shaped section; thereafter finishing the Y-shaped sections to formeach of them into a T-shaped section; and joining two of the rolledflange pieces together via a profiled surface of each flange piece.
 7. Amethod according to claim 1, further comprising providing the web as acorresponding rolled web piece and joining the rolled flange pieces viathe rolled web piece.
 8. A method according to claim 1, furthercomprising the rolling comprises one or more rolls rolling the stock,and manipulating the one or more rolls then rolling the stock during therolling operation to vary individual beam dimensions of at leastthickness of at least one of a flange and/or the web along the beamlength.
 9. A method according to claim 1, further comprising casting rawmaterial with at least part of the required thickness variation alreadypresent in the cast material and rolling the cast material.
 10. A methodof manufacturing a beam, the method comprising: rolling, in alongitudinally profiled rolling process, two separate flange pieces,such that at least one surface of each rolled flange piece is profiledaccording to a predetermined thickness profile of the flange; orientingthe flange pieces to have their respective at least one profiled surfaceof each flange facing toward the other flange; and joining the rolledflange pieces together.
 11. A method according to claim 4, wherein ashape of each of the flange pieces includes a stem that extends towardthe stem of the other flange piece.
 12. A method according to claim 7,further comprising rolling the flange piece by rolls and at least one ofthe rolls having two parts separated in the longitudinal directionproviding a gap between the separated parts of the at least one roll,and rolling a flange piece to develop a stem during the rolling of theflange and to have the stem extend into the gap between the twoseparated parts of the at least one roll.
 13. A method according toclaim 12, further comprising at least two of the rolls for rolling theflanges, each of the two rolls having two separated parts, wherein eachroll is for rolling a respective flange piece; adjusting the at leasttwo rolls to have the stem of each of the two flanges being rolledextend into the same gap between the two roll parts of each of the atleast two rolls for the stem of each flange to extend toward the stem ofthe other flange.
 14. The method according to claim 13, furthercomprising welding the stems extending toward each other to each other.15. The method according to claim 1, further comprising rolling the webin a longitudinally profiled rolling process such that the web isprofiled according to a predetermined thickness of the web.
 16. Themethod according to claim 15, further comprising the web having oppositeedges along the longitudinal direction of the web which define a depthof the web and the method further comprising: rolling the web to have alongitudinally profiled depth between the flanges that is variable, suchthat the depth of the web along the opposite edges of the web that arerespectively toward the flanges are profiled to receive the profiles ofthe thickness of the respective flanges where the flanges are at theedges of the web.
 17. The method according to claim 1, wherein theflanges are rolled with respective profiled surfaces that face eachother with matching thickness profiles.
 18. The method according toclaim 1, wherein the web and flanges are welded to each other alonglongitudinal edges of the web to define the beams.